gearbox stuck in reverse

hello has anyone ever had a problem with the gearbox getting stuck in reverse?i think its my fault as i dropped the plastic speedo drive into the gearbox and thought,it being plastic,that it would just get broken up by the gears!!i have now unbolted everything to get the box out,but 2 bolts on passenger side drive shaft wont undo at all!!have i got to drill these out and re tap a thread or is there another way of getting them out?thanks in advance ops:

Grind the heads off the bolts, then replace with new ones on refitting. Once the heads are off, and the driveshaft out the way, the rest of the bolt will be easy to unscrew using mole grips/similar.

cheers paul for the quick reply.i did think of that but thought i would have to drill out the rest of the bolt,but the thickness of the drive shaft flange would leave a bit of bolt sticking out.nice one,cheers.dont suppose you have a gearbox for sale and live in kent? :wink:

i had this prob only once it has not happened since all i did was pop of selector and tapped the arm with a heavy hammer took 3 knocks